The present invention relates to a rotary connector device for electrically connecting a stator member, such as steering column of an automobile, to a rotor member, such as steering wheel.
Japanese Patent Publication laid-open Nos. 2003-151711 and 2003-243119 disclose this kind of rotating connector devices. Each of the rotating connector devices comprises a stator fixed to a steering column, a rotor fixed to a steering wheel and rotatably assembled to the stator, a cable chamber arranged in the rotor and the stator and formed circumferentially around a rotating center of the rotor, a flexible flat cable accommodated in the cable chamber so as to allow a rotation of the rotor, the flexible flat cable having one end led toward the stator and the other end led toward the rotor, and a slip-ring mechanism. The slip-ring mechanism includes conductive rings fixed to the rotor and arranged around the rotating center of the rotor and sliding terminals arranged on the stator to slide on the conductive rings.
In operation, when the steering wheel is rotated, the rotor rotates in relation to the stator. For the rotation of the rotor, the flexible flat cable maintains an electrical connection between the stator and the rotor while changing its accommodated condition in the cable chamber. On the other hand, the sliding terminals maintain the electrical connection between the stator and the rotor while sliding on the conductive rings. In case of small conducting current flowing between the steering column and the steering wheel (e.g. ignition signal for air bag), a conducting route in the flexible flat cable is employed. To the contrary, in case of large conducting current (e.g. current for steering heater), a conducting route in the slip ring mechanism is employed.
Meanwhile, the above slip ring mechanism is positioned below the cable chamber in the following manner. In case of Japanese Patent Publication laid-open No. 2003-151711, a rotor has a shaft part formed to project from a cable chamber downwardly. The shaft part is provided with a projecting brim part to which conducting rings are fixed. On the other hand, a stator has a projecting part formed to project from the cable chamber downwardly. Terminal attachments are fixed to the projecting part of the stator by screws. The above-mentioned sliding terminals are fixed to the terminal attachments.
In the above-constructed slip ring mechanism, however, the number of components forming the mechanism is large to cause a rise in its manufacturing cost due to the structure where the sliding terminals are attached to the stator with the use of the sliding terminals. Additionally, since it is necessary to provide the stator with an exclusive space below the cable chamber to accommodate the slip ring mechanism, a dimension of the rotary connector device is increased in its axial direction, causing the device to be large-sized. Further, as mentioned above, the rotor has to be provided, as an exclusive attachment portion, with the brim part for the conductive rings of the slip ring mechanism.